Expansible tube tensilizing apparatus



-.Ian- 8, 95 H. ROSENFELD EXFANSIBLE TUBE TENSILIZING APPARATUS Filed April 5, 1950 INVENTOR.

WWXWW ATTORNEY 5'.

Patented Jan. 8, 1952 EXPANSIBLE TUBE TENSILIZING APPARATUS Harry Rosenfeld, Brooklyn, N. Y., assignor to Milprint, Inc., Milwaukee, Wis., a corporation of Delaware Application April 5, 1950, Serial No. 154,052

2 Claims. 1

The present invention relates generally to im-- provements in the art of producing tubing from expansible sheet materials, and relates more particularly to an improved apparatus for the con tinuous production of expanded thermo-plastic tubing;

A primary object of this invention is to providean improved simple, compact and durable apparatus for rapidly and efficiently continuously producing expanded and set tubing from normally stretchable or expansible thermo-plastic sheet materials.

It has long been customary to wrap or package diverse commodities in various types of protective receptacles, and it is likewise common practice to enclose commodities such as meats and sausages in artificial casings formed of stretchable plastic sheet materials in tubular form. These protective receptacles and/or casings may be conveniently produced from sections of seamed or seamless tubing, and one of the thermo-plastic or elastomer materials frequently utilized because of its inherent qualities of edibility and receptiveness to printing is a rubber hydrochloride known commercially as Pliofilm. However, while Pliofilm and other materials of the elastomer group are known to possess desirable qualities and are therefore extensively used for this purpose, these materials are quite expansible and will stretch undesirably out of direct contact with the wrapped or packaged articles unless such sheet materials are specially treated as by a stretching process in the presence of heat.

In the use of tubing fabricated of thermoplastic or elastomer sheet materials, it has here tofore been common practice either to prepare the tubing by stretching the same preparatory to utilization in packing or to perform the stretch-' ing and setting operation during the application of the tubing to the product. In the customary method of preparing the tubing prior to packing of the product, the tubing is first cut into the desired lengths; then each section is indixidually slipped lengthwise onto an expanding bar or mandrel; thereafter, the bar and tube section is inserted into a tank of warm water; while immersed in the warm liquid, the bar or mandrel is expanded laterally causing the tubing section to likewise expand; and finally the bar and expanded tube section are removed from the hot water and are inserted, while in expanded condition, into cold water to set the tubing. When the tubing is stretched and set during the application thereof to the product, the usual practice is likewise to first sever the same into the desired lengths; thereafter, the tubing sections may be independently subjected to a wetting action inv batch methods as distinguished from a continuous process, since the tube of expansible material is severed into sections in each instance with each individual section being subsequently treated. Consequently, one of the main disadvantages of these prior methods is that they both require time consuming hand operations which are slow and costly. Furthermore, the casings stretched'by such methods are not uniform due to the lack of control of the amount of stretch or expansion, and a large percentage of casings must therefore be scrapped. Another very important objection to the prior methods is that the casings produced thereby must be hand fed on a platen press for printing because of the fact that they are cut into sections for individual treatment, and this is also a time consuming and costly operation.

It is therefore a more specific object of the present invention to provide animproved apparatus for continuously producing expanded and set tubing which obviates all of the disadvantages attendant prior methods and apparatus.

Another specific object of the invention is to provide an improved tubing stretching and setting apparatus which may' be operated economically and in a rapid and continuous manner with the aid of minimumpersonnel.

Another specific object of this invention is to provide an improved apparatus for continuously treating normally expansible tubing to expand and set the same under readily controllable con: ditions to uniform diameters and with uniform tensilization throughout the entire tubing wall.

Another specific object of my invention is to provide an improved apparatus for continuously expanding and setting normally expansible tubing, whereby rolls of tensilized tubing may be readily produced which may subsequently be printed in a rapid manner on a rotary press at minimum cost.

Still another specific object of the invention is to provide an improved apparatus for continuously tensilizing normally expansible tubing which is extremely simple and inexpensive in construction, which may be economically and efiiciently operated by a novice, and which is composed of relatively few parts all of which are readily accessible for adjustments, replacement and/or repair.

An additional specific object of the present invention is to provide an improved expansible tube tensilizing apparatus comprising, means for longitudinally advancing a flat tube of expansible material, means for heating successive portions of the tube, means for successively laterally stretching the heated portions of the tube a predetermined distance, and means for cooling the tube while in stretched condition.

These and other objects and advantages of the invention will be apparent from the following detailed description.

A clear conception of the several steps involved in the production of tensilized or expanded tubing, and of typical apparatus for effecting commercial exploitation, may be had by referring to the drawing accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the several views.

Fig. l is a more-or-less diagrammatic side view of a typical apparatus in accordance with the invention, the hot and cold water tanks being shown in section so as to clearly reveal normally concealed structure and the several successive steps of the method; and

Fig. 2 is a similar diagrammatic top view of the apparatus and likewise depicting the successive production steps involved in the method of operating the same.

While the improvement has been particularly described herein as being advantageously applicable in the continuous production of transversely tensilized or expanded tubing formed or Pliofilm or the like and especially adapted for encasing food products, it is not desired or intended to unnecessarily limit the invention by virtue of such restricted application, since the improved apparatus may be utilized to advantage in preparing tubing formed of other thermo-plastic or elastomer materials and intended for packaging diverse products.

In accordance with my present method of tensilized tubing production, I initially longitudinally advance a fiat tube of normally expansible thermo-plastic or elastomcr material along a given path. As the flattened tube is advanced, the successive portions thereof are subjected to heat, as by immersion in a bath of water heated to between 130 to 175 degrees Fahrenheit, to soften and render the material more plastic, and this step may be performed as the tube is continuously advanced. Thereafter, the heated portions of the tube are successively laterally stretched, transversely of the opposite edges thereof a predetermined distance while still in heated condition, and this step may likewise be performed in a continuous manner by gripping the opposite tube edges and gradually spreading the same apart as the flattened tube is advanced. Finally, the tube is cooled while in stretched condition to set the same, and this may be conveniently accomplished by continuously passing the advancing prestretched tube through a cold water bath after which the expanded and set tubing may be rewound for subsequent printing if desired.

When carrying on commercial exploitation of this 'tensilized tubing production method, I prefer to utilize an installation substantially like that shown diagrammatically in the accompanying drawing. Referring to the drawing, the initial unstretched and normally expansible seamed or seamless tubing 5 of thermo-plastic or elastomcr material may be supplied from a rotatably supported roll 6 from which the tubing 5 may be continuously or intermittently withdrawn and longitudinally advanced in flat condition over suitably arranged guide rollers 1; means such as a rotatably supported drum 3 having a peripheral tube guiding surface adapted to advance through a controllable bath of hot liquid contained within a suitable tank 9 to subject the successive portions of the tube 5 to heat to initially soften the same; other suitably arranged guide rollers l9 over which the heated tubing may subsequently be longitudinally advanced to stretching means such as a pair of angularly disposed or relatively inclined revolvable disks H adapted to coact with the opposite edges of the flattened tube 5 to successively laterally stretch the heated portions thereof a predetermined distance; and cooling means such as a rotatably supported drum 13 to which the advancing pre-stretched tube 5 may be guided by suitably arranged rollers l2 or the like, the drum [3 having a peripheral tube engaging surface adapted to advance through a controllable cold liquid bath contained within a suitable tank It for setting the successive stretched or expanded portions of the tubing 5.

The finally expanded or stretched and set tubing 5 may thereafter be guided by means of rollers i5 or the like to a rotatable rewind roll i6, and the tubing may obviously be advanced through the several successive steps by means of either the drums 8 and I3 or by selected ones of the rollers 'a', H1, H2 and I5, one or more of which may be driven in any suitable manner. Since the stretching or expanding disks H are angularly disposed relative to each other and relative to the edges of the tubing, these disks act to gradually transversely spread the tubing continuously as it advances; and to insure positive gripping of the tube edges by the spreading elements, the disks H are preferably each provided with a peripheral groove ll adapted to receive an endless belt 18, the tube edges being gripped between the disk peripheries and the respective belts IS. The disks H may obviously be mounted to permit angular adjustment so as to vary the amount of stretch desired, and the belts 18 which may be supported by suitable pulleys or sheaves l9 may likewise be rendered adjustable so as to operate in the same plane as the corresponding disk as well as to vary the tension of the respective belts. To maintain the successive heated portions of the advancing tubing 5 in softened or pliable condition after immersion in the hot water by the drum 8 and just prior to the stretching operation, the tube may be subjected to a spray of hot liquid from a nozzle 20; and to insure maintenance of such softened condition during the stretching operation, the disks H and belts It; may be partially immersed in the hot liquid bath in the tank 9. Likewise, the setting operation may be initiated immediately upon completion of the stretching step by subjecting the expanded casing 5 to a cold liquid spray from a nozzle 2! directly following the stretching and before immersion thereof in the cold water bath. In addition to the expansion of the tube transversely of its opposite edges by means of the angularly disposed disks H and belts !8, the tubing 5 may be subjected to controlled longitudinal stretching, if desired, by adjusting the drum 8 and the rollers ID to vary the longitudinal tension on the heated tube 5 during its advancement.

From the foregoing detailed description it will be apparent that my present invention provides improved apparatus for commercially producing expanded tubing which is extremely simple and efllcient in the rapid and continuous production of tensilized tubing at low cost. Through utilization of the improved apparatus in the production of tensilized tubing, rolls of tubing of thermo-plastic or elastomer materials may be produced which may be quickly and economically printed on a rotary press for subsequent utilization without further treatment by the packer; and the typical apparatus disclosed herein is adapted to effectively carry out the successive steps of the production method in an intermittent or continuous manner under readily controllable conditions and with minimum attention. The improved apparatus has, in fact, proven highly successful in actual commercial use, and it may obviously be modified for utilization of hot and cold air, or other fluid treating mediums, instead of hot and cold water as described. The apparatus is furthermore extremely compact and durable a well as simple in construction, and all of the parts are readily accessible for inspection, adjustment and/or repair. With the improved apparatus, the normally expansible tubing 5 may be tensilized or expanded and set to a uniform desired width throughout its length in a continuous manner without need for first severing the same into individual sections for time consuming and expensive separate or batch treatment, and the final roll l6 of tubing may be easily handled, printed and merchandised. As indicated, the disks II and belts [8 may be rendered adjustable to impart the desired amount of predetermined stretch to the tube as well as to place more or less gripping pressure on the edges of the tube during the stretching operation, and the nozzles 20, 2| may or may not be provided.

It should be understood that it is not desired or intended to limit this invention to the precise details of the apparatus, herein shown and described, for various modifications within the scope of the appended claims may occur to persons skilled in the art to which this invention pertains; and it is also contemplated that specific descriptive terms used herein be given the broadest possible interpretation consistent with the disclosure.

. I claim:

1. An expansible tube tensilizing apparatus comprising, a pair of drums rotatable about spaced horizontal axes, one of said drums being partially immersed in a heated liquid bath and the other of said drums being partially immersed in a cool liquid bath, means for longitudinally advancing a continuous flattened tube of expansible material from said one drum to the other, and a pair of angularly disposed revolvable disks located between said drums and adapted to coact with the opposite edges of said flattened tube to laterally spread said tube as it advances, said disks being likewise partially immersed in the same heated liquid bath as said one drum.

2. An expansible tube tensilizing apparatus comprising, a pair of drums rotatable about spaced horizontal axes, means for subjecting one of said drums to an external liquid heating medium, means for subjecting the other of said drums to an external liquid cooling medium, means for longitudinally advancing a continuous flattened tube of expansible material from said one drum to the other, and means located between said drums and adapted to coact with the opposite edges of said flattened tube to laterally spread said tube as it advances, said tube spreading means being likewise subjected to the same heating medium as said one drum.

HARRY ROSENFEL REFERENCES CITED The following references are of record in the 

